Navigation apparatus and server apparatus

ABSTRACT

A navigation apparatus acquires geographic information from a server apparatus. When the navigation apparatus does not store any geographic information that provides a continuous route from the starting point to a destination point, it transmits data of the starting point and destination point to the server apparatus to acquire therefrom geographic information that provides a continuous route from the starting point to the destination point. This efficient acquisition of geographic information realizes reduction of communication time and communication costs.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a National Stage entry of International ApplicationNumber PCT/JP03/07582, filed Jun. 13, 2003. The disclosure of the priorapplication is hereby incorporated herein in its entirety by reference.

TECHNICAL FIELD

The present invention relates to a navigation apparatus that acquiresmap information through communication, and also relates to a serverapparatus that transmits map information to such a navigation apparatus.

BACKGROUND ART

There are conventionally known route guiding systems that guide peoplealong a route by providing them with map information and otherinformation. For example, navigation methods that rely on mobilecommunication involving a mobile device, incorporating a globalpositioning system receiver, and a control station, incorporating adatabase of map information and other information, work in the followingmanner. The mobile device transmits to the control station locationinformation and destination information, based on which the controlstation then retrieves from the database a map around the currentlocation and a route to the destination location. The thus retrievedroute information is transmitted back to the mobile device and isdisplayed on the display section thereof. This permits route guiding tobe performed with enhanced accuracy, permits the user to acquire theinformation they need whenever they need it, and permits the user to beprovided with various kinds of information that they may need other thanmap information (see, for example, Japanese Patent Application Laid-OpenNo. 2000-213952).

Some conventional navigation systems relying on communication involve aroute guiding device, built as a car-mounted or hand-held unit andfunctioning as a terminal station, and a route information providingdevice, built as an information center and functioning as a basestation, and these navigation systems work as follows. Between the routeguiding device and the route information providing device, data such aslocation information and route guiding information is exchanged throughcommunication so that the route guiding device is fed with informationabout a route to the destination location. In this way, route guiding isachieved. Here, of the retrieved route, not all but only part that theroute guiding device has not yet traveled is selectively exchanged (see,for example, Japanese Patent Application Laid-Open No. 2000-18955).

However, the method disclosed in Japanese Patent Application Laid-OpenNo. 2000-213952 mentioned above has the following disadvantages. It isall the map information related to the retrieved route that the controlstation transmits to the mobile device. Thus, a large quantity of dataneeds to be transmitted through a lengthy communication session,resulting in increased communication costs and long processing time. Inparticular, in cases where the distance from the current location to thedestination location is long, the increases in communication time andcommunication costs are too large to ignore. Moreover, the lengthycommunication session tends to invite heavy communication traffic,leading to trouble such as garbled or aborted communication.

On the other hand, communication-dependent navigation systems like theone disclosed in Japanese Patent Application Laid-Open No. 2000-18955mentioned above have the following disadvantages. The user oftenremembers, as known routes, routes that they have ever traveled, andtherefore they are unlikely to have much difficulty to reach adestination if provided with only the map information related to thepart of the route thereto that they have never traveled before, even ifthey are not provided with the map information related to the known partthereof. With this system, however, even when the user seeks routeguiding but do not actually head for the destination, the retrievedroute will be, when the same route is retrieved next time, treated as aknown route. Thus, the user cannot acquire the related map information.This can be prevented by notifying the route information providingdevice of the routes that have actually been traveled. This, however,requires that the information related to the ever traveled routes betransmitted to the route information providing device, resulting inextra communication costs.

Incidentally, some car-mounted navigation apparatuses have guideinformation related to sightseeing spots, gas stations, and the likestored on a recording medium such as a DVD. For the propose ofcomplementing such guide information in terms of quantity andupdatedness, it has been proposed to download additional and updatedguide information through communication (see, for example, JapanesePatent Application Laid-Open No. H11-266329). It has also been proposedto add advertisements to such guide information. It has further beenproposed to show such guide information on a small screen such as thoseon cellular phones and PDAs (personal digital assistants). Theseproposals, however, greatly increase the quantity of guide informationhandled, now containing advertisements, and thus make it uncomfortablefor the user to view the desired guide information, particularly when itis shown on a small display screen.

DISCLOSURE OF THE INVENTION

In view of the conventionally experienced inconveniences describedabove, it is an object of the present invention to provide a navigationapparatus that operates with reduced communication time and reducedcommunication costs. It is another object of the present invention toprovide a navigation apparatus that permits the user to easily reach thedesired items of information among a large quantity of guideinformation. It is still another object of the present invention toprovide a server apparatus that transmits information to such navigationapparatuses.

To achieve the above objects, according to the present invention, anavigation apparatus achieves route guiding by acquiring from a serverapparatus map information from a start location to the destinationlocation.

Here, the acquired map information is, for example, a map consisting ofunit areas that covers a rectangular area of which two diagonal verticescoincide with the start and destination locations, or a map consistingof unit areas that covers an area including and neighboring a retrievedroute. Acquiring only map information that is not stored in thenavigation apparatus helps eliminate unnecessary informationacquisition. With respect to map information that is stored in thenavigation apparatus, if a version thereof having a later creationdate-time is found in the server apparatus, it is preferable to acquirethis version to update the older stored in the navigation apparatus.This benefits the user.

A search for a route from the start location to the destination locationmay be performed on the navigation apparatus, or may be performed on theserver apparatus with the result of the search then transmitted to thenavigation apparatus.

The user may be offered additional services in the form of displays ofadvertisements and service information related to what is availablealong and near the retrieved route. Here, to restrict the quantity ofinformation displayed on the navigation apparatus, first the serverapparatus transmits search data to the navigation apparatus, and thenthe user enters search conditions so that these are transmitted back tothe server apparatus. In this way, it is possible to acquire only thedesired guide information.

The search data includes, for example, date-time restricting data, timerestricting data, and location data. This makes it possible to performdetailed searches.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram showing the configuration of a communicationsystem according to the invention.

FIG. 2 is a block diagram showing the configuration of the navigationapparatus of a first and a second embodiment of the invention.

FIG. 3 is a flow chart showing the operation of the navigation apparatusand the server apparatus in the first embodiment.

FIG. 4 is a diagram showing an example of the map information andplanned travel route stored in a navigation apparatus according to theinvention.

FIG. 5 is a diagram showing another example of the map information andplanned travel route stored in a navigation apparatus according to theinvention.

FIG. 6 is a diagram showing an example of the map information, currentlocation, and destination location stored in a navigation apparatusaccording to the invention.

FIG. 7 is a diagram showing the acquired map information and plannedtravel route superimposed on FIG. 6.

FIG. 8 is a flow chart showing the operation of the navigation apparatusand the server apparatus in the second embodiment.

FIG. 9 is a flow chart showing the operation of the navigation apparatusand the server apparatus in a third embodiment of the invention.

FIG. 10 is a block diagram showing the configuration of the navigationapparatus of a fourth embodiment of the invention.

FIG. 11 is a diagram showing the items set as search conditions and thesearch data in the fourth embodiment.

FIG. 12 is a flow chart showing the operation of the navigationapparatus in the fourth embodiment.

FIG. 13 is a flow chart showing the detailed operation of step S66 shownin FIG. 12.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described withreference to the drawings. FIG. I is a block diagram showing theconfiguration of a communication system. Reference numeral 10 representsa navigation apparatus, reference numera11 represents a server apparatusthat communicates with the navigation apparatus 10, and referencenumeral 12 represents a database that is connected to the serverapparatus 1. The database 12 contains map information 13. The database12 may be provided within the server apparatus 11.

On receiving a request from the navigation apparatus 10, the serverapparatus 11 reads out map information 13 from the database 12 andtransmits it to the navigation apparatus 10. The communication betweenthe navigation apparatus 10 and the server apparatus 11 may be achievedin any manner so long as it is achieved wirelessly. For example, in acase where their communication is conducted over the Internet, it ispossible to use a telephone network for car phones, cellular phones, orthe like.

FIG. 2 is a block diagram showing the configuration of the navigationapparatus 10. Reference numeral 20 represents a current locationdetector that obtains information about the current location, traveldirection, speed, altitude, and the like by using a GPS receiver, aspeed sensor, a gyro, and the like. Reference numeral 21 represents acommunication controller that controls the communication with the serverapparatus 11. Reference numeral 22 represents an antenna that isconnected to the communication controller 21 and that is used to conductwireless communication.

Reference numeral 23 represents a display section composed of a liquidcrystal display or the like for displaying map information and thecurrent location. Reference numeral 24 is an operation section throughwhich the user enters data as for setting the destination location.Reference numeral 25 represents a map information storage section inwhich are stored map information along with the creation date-timethereof that the map information includes as basic information. Itshould be noted that the date-time of map information is not always thedate-time at which it was created, but also the date-time at which itwas updated as when a now road was constructed.

Reference numeral 26 represents a RAM in which the destination location,planned travel route, and the like are temporarily stored. Referencenumeral 27 represents a ROM in which the programs needed for thenavigation apparatus 10 to operate are stored. Reference numeral 28represents a controller composed of a microcomputer or the like thatcontrols the navigation apparatus 10 according to the programs stored inthe ROM 27. The map information storage section 26 is realized with astorage medium such as a DRAM.

Hereinafter, embodiments of the communication system described abovewill be described.

First Embodiment

The operation performed by the communication system to perform routeguiding in a first embodiment of the invention will be described. FIG. 3is a flow chart showing the operation of the navigation apparatus 10 andthe server apparatus 11. First, the user, by operating the operationsection 24 of the navigation apparatus 10, enters the destinationlocation, and presses a route search execute key (not illustrated). Inresponse, in step S10, the navigation apparatus 10 stores thedestination location in the map information storage section 25, andthen, in step S11, based on the location information of the current anddestination locations and the map information stored in the mapinformation storage section 25, the map information storage section 25checks whether or not continuous map information from the currentlocation to the destination location is stored.

The destination location can be entered, for example, by specifying anaddress or telephone number, or by pointing on the displayed map. Whenthe user chooses to point on the map, it may occur that the mapinformation storage section 25 does not have map information that coversthe desired destination location. In this case, the map informationaround the destination location can be acquired from the serverapparatus 11.

If, in step S11, it is found that continuous map information from thecurrent location to the destination location is stored in the mapinformation storage section 25, then, in step S12, the controller 28performs a route search by using the map information stored in the mapinformation storage section 25. On completion of the route search, instep S13, the current location and planned travel route are superimposedon the map information displayed on the display section 23. Thereafter,the screen is scrolled as the current location moves, and route guidingis continued until the destination location is reached.

Here, it is assumed that, when the route guiding is performed, thenavigation apparatus 10 has map information around the current locationpreviously stored in the map information storage section 25. The mapinformation may be either that which has been stored since thenavigation apparatus 10 was used last time or that which is obtained byautomatically receiving map information around the current location (forexample, within the 5 km radius area of the current location) when thenavigation apparatus 10 is turned on.

On the other hand, if, in step S11, it is found that continuous mapinformation from the current location to the destination location is notstored in the map information storage section 25, that is, if the mapinformation stored there is found to be discontinuous even only partly,then, in step S14, the conditions for a route search, including thelocation information of the current and destination locations and thearea covered by the map information stored in the map informationstorage section 25, are transmitted to the server apparatus 11.

On completion of step S14, in step S20, the server apparatus 11 receivesthe conditions for a route search from the navigation apparatus 10, andthen, in step S21, the server apparatus 11 accesses the database 12 andperforms a route search from the current location to the destinationlocation.

Next, in step S22, the map information along the calculated travel routeis compared with the area of the map information received from thenavigation apparatus 10, and, from the former, the part that is notstored in the navigation apparatus 10 is extracted. Then, in step S23,the planned travel route calculated in step S21 and the map informationextracted in step S22 are transmitted to the navigation apparatus 10.

On completion of step S23, in step S15, the navigation apparatus 10receives the planned travel route and map information from the serverapparatus 11, and stores them in the map information storage section 25.Then, in step S13, by the use of the planned travel route and mapinformation thus obtained, route guiding is performed.

As described above, if, in the course of route guiding, continuous mapinformation from the current location to the destination location isstored in the navigation apparatus 10, a route search is performedwithin the navigation apparatus 10. This makes it possible to performroute guiding without conducting communication, and thus eliminates theneed to worry about the communication time and communication costs. Onthe other hand, if continuous map information from the current locationto the destination location is not stored in the navigation apparatus10, what needs to be acquired from the server apparatus 11 is only theplanned travel route and the part of the map information that is notstored in the map information storage section 25. This helps reduce thecommunication time and communication costs.

For example, in a case where at least map information 30 to 38 as shownin FIG. 4 is stored in the map information storage section 25, when acurrent location X and a destination location Y are set and a routesearch is requested, since continuous map information from the currentlocation X to the destination location Y is stored in the mapinformation storage section 25, the route search is performed within thenavigation apparatus 10, and a planned travel route 39 as shown in FIG.4 is calculated. In the figure, the individual blocks 30 to 38 of themap information represent units of map information, and no informationother than that related to the planned travel route is shown.

For example, in a case where map information 30 to 32, 35, and 38 asshown in FIG. 5 is stored in the map information storage section 25,when a current location X and a destination location Y are set and aroute search is requested, since continuous map information from thecurrent location X to the destination location Y is stored in the mapinformation storage section 25, the route search is performed within thenavigation apparatus 10, and a planned travel route 40 as shown in FIG.5 is calculated. In this way, although FIG. 5 lacks the map information34 and 37 shown in FIG. 4, it still has continuous map information fromthe current location X to the destination location Y, and thus the routesearch is performed by the use of that map information. This results ina planned travel route 40 different from the planned travel route 39 inFIG. 4.

For example, in a case where map information 30 to 32 and 38 as shown inFIG. 6 is stored in the map information storage section 25, when acurrent location X and a destination location Y are set and a routesearch is requested, since continuous map information from the currentlocation X to the destination location Y is not stored in the mapinformation storage section 25, the navigation apparatus 10 transmitsroute search conditions to the server apparatus 11. The server apparatus11 then performs a route search, calculates a planned travel route 39 asshown in FIG. 7, extracts map information 34 and 37 from the database12, and transmits them to the navigation apparatus 10. In this way, theplanned travel routes 39 in FIGS. 7 and 4 are the same, but aredifferent from the planned travel route 40 in FIG. 5. The planned travelroute 39 is shorter than the planned travel route 40, and can thus besaid to be the optimum route.

That is, in a case where, as in FIG. 4, all the neighborhood map up tothe destination location is stored in the map information storagesection 25, the optimum route can be retrieved within the navigationapparatus 10. By contrast, in a case where, as in FIG. 5, onlyparticular parts of the map information up to the destination locationare stored in the map information storage section 25, a route search canbe performed within the navigation apparatus 10, but the retrieved routeis not always the optimum route. Accordingly, to retrieve the optimumroute, it is necessary to perform a route search in the server apparatus11 at extra costs and with longer communication time.

Second Embodiment

As a second embodiment of the invention, a description will be givenbelow of a navigation apparatus 10 that permits the choice of whether toperform a route search on the navigation apparatus 10 or on the serverapparatus 11.

FIG. 8 is a flow chart showing the operation of the navigation apparatus10 and the server apparatus 11 in the second embodiment. Here, suchsteps as find their counterparts in FIG. 3 are identified with the samereference numerals, and their detailed explanations will not berepeated.

If, in step S11, it is found that continuous map information from thecurrent location to the destination location is stored in the mapinformation storage section 25, then, in step S30, whether or not itincludes neighborhood map information is indicated. Specifically, aquadrilateral (for example, rectangular) map of which two diagonalvertices coincide with the current and destination locations isdisplayed, with those parts thereof that are not stored in the mapinformation storage section 25 displayed in black, white, or the like soas to be recognizable as such. The thus displayed image is, for example,like the one shown in FIG. 5 with the planned travel route 40 deleted.

Based on the thus displayed indication of whether or not particularparts of the map are stored, the user chooses whether to perform theroute search on the navigation apparatus 10 or on the server apparatus11, and enters their choice by operating the operation section 24. Here,if the displayed parts of the map is rather few, it is better to performthe route search on the server apparatus 11 to surely obtain the optimumroute.

After step S30, in step S31, which choice has been made, whether toperform the route search on the navigation apparatus 10 or on the serverapparatus 11, is checked. If, in step S31, it is found that the routesearch has been chosen to be performed on the navigation apparatus 10,then the flow proceeds to step S12. By contrast, if in step S31, it isfound that the route search has been chosen to be performed on theserver apparatus 11, then the flow proceeds to step S14.

In a case where the route search is performed on the server apparatus11, as the flow proceeds through steps S14 to S22 to step S32, theplanned travel route calculated in step S21 and the map informationextracted in step S22 are transmitted to the navigation apparatus 10.

As described above, even when the map information up to the destinationlocation is stored in the map information storage section 25, bypermitting the choice of whether to perform a route search on thenavigation apparatus 10 or on the server apparatus 11, it is possible topermit the choice between whether to give priority to reducing thecommunication time and communication costs or to surely obtain theoptimum planned travel route.

In the second embodiment, a route search is described as being performedfrom the current location to the destination location. Instead, it isalso possible to set a start location and a destination location througha similar flow of operations. This makes it possible to perform a routesearch starting at the desired start location.

Step S30 is not absolutely necessary; that is, the user may be requestedto make a choice without a displayed indication. Alternatively, it isalso possible to omit step S30 and let the controller 28 automaticallymake a choice based on the amount of map information or the like in stepS31. A choice can be made automatically, for example, by letting theserver apparatus automatically perform a route search if any part of themap information containing a quadrilateral (for example, rectangular)map of which two diagonal vertices coincide with the starting (orcurrent) location and the destination location is missing.

There may be cases where step S21 is not necessary. For example, in acase where the server apparatus 11 acquires the map information of aquadrilateral area of which two diagonal vertices coincide with thestarting and destination locations, there is no need to perform a routesearch on the server apparatus; instead, after the acquisition of themap information, a route search is performed on the navigation apparatus10.

If, in step S11, it is found that the map information up to thedestination location is stored, after a route search is performed on thenavigation apparatus 10, the map information of unit areas neighboringthe planned travel route may be acquired from the server apparatus sothat the navigation apparatus 10 then performs a route search once againbefore starting route guiding. Even if a route that is not the shortest,like the planned travel route 40 in FIG. 5, has been calculated, byacquiring neighborhood map information and then performing a routesearch once again, it is possible to calculate the shortest route likethe planned travel route 39 in FIG. 4.

Third Embodiment

Now, the operation performed by the communication system to performroute guiding in a third embodiment of the invention will be described.FIG. 9 is a flow chart showing the operation of the navigation apparatus10 and the server apparatus 11. Here, such steps as find theircounterparts in FIG. 3 are identified with the same reference numerals,and their detailed explanations will not be repeated.

If, in step S11, it is found that continuous map information from thecurrent location to the destination location is stored in the mapinformation storage section 25, then, in step S40, the controller 28transmits to the server apparatus 11 information about the creationdate-time of the map information from the current location to thedestination location that is stored in the map information storagesection 25.

On completion of step S40, in step S50, the server apparatus 11 receivesthe information, transmitted from the navigation apparatus 10, about thecreation date-time of the map information stored therein. Then, in stepS51, the server apparatus 11 accesses the database 12 to compare thecreation date-time. Then, in step S52, if the creation date-time of themap information stored in the navigation apparatus 10 as receivedtherefrom is identical with that of the map information 13 stored in thedatabase 12, the server apparatus transmits to the navigation apparatus10 information indicating that no updating is needed; if the former isolder than the latter, the server apparatus 11 reads out new mapinformation from the database 12 and transmits it to the navigationapparatus 10.

On completion of step S52, in step 41, according to instructions fromthe controller 28, the navigation apparatus 10 receives the new mapinformation from the server apparatus 11, and stores it in the mapinformation storage section 25. Here, it is preferable that the old mapinformation be overwritten with the new map information. Here, if thenavigation apparatus 10 receives from the server apparatus 11information indicating that no updating of the map information isnecessary, it does not receive any map information.

On completion of step S41, in step S12, the controller 28 performs aroute search by the use of the map information stored in the mapinformation storage section 25. On completion of the route search, then,in step S13, the current location and planned travel route aresuperimposed on the map information displayed on the display section 23.Thereafter, the screen is scrolled as the current location moves, androute guiding is continued until the destination location is reached.

On the other hand, if, in step S11, it is found that continuous mapinformation from the current location to the destination location is notstored in the map information storage section 25, that is, if the mapinformation stored there is found to be discontinuous even only partly,then, in step S14, the conditions for a route search, including thelocation information of the current and destination locations and thearea covered by the map information stored in the map informationstorage section 25, are transmitted to the server apparatus 11.

On completion of step S14, in step S20, the server apparatus 11 receivesthe conditions for a route search from the navigation apparatus 10, andthen, in step S21, the server apparatus 11 accesses the database 12 andperforms a route search from the current location to the destinationlocation.

Next, in step S22, the map information along the calculated travel routeis compared with the area of the map information received from thenavigation apparatus 10, and, from the former, the part that is notstored in the navigation apparatus 10 is extracted. Then, in step S53,whatever part of the map information along the planned travel routestored in the map information storage section 25 has a later creationdate-time than the map information stored in the map information storagesection 25 is read out.

Then, in step S23, the planned travel route calculated in step S21 andthe map information extracted in steps S22 and S53 are transmitted tothe navigation apparatus 10.

On completion of step S23, in step S15, according to instructions fromthe controller 28, the navigation apparatus 10 acquires from the serverapparatus 11 the planned travel route and map information, and storesthem in the map information storage section 25. Thereafter, in step S13,by the use of the planned travel route and map information thusobtained, route guiding is performed.

As described above, if, in the course of route guiding, continuous mapinformation from the current location to the destination location isstored in the navigation apparatus 10, the navigation apparatus 10transmits to the server apparatus 11 the creation date-time of the mapinformation stored in the map information storage section 25. Thus, thenavigation apparatus 10 acquires map information only when an updatedversion thereof is available. In this way, it is possible to perform aroute search within the navigation apparatus 10 by always using the mostrecent map information, while reducing the communication time andcommunication costs. On the other hand, if continuous map informationfrom the current location to the destination location is not stored inthe navigation apparatus 10, what needs to be acquired from the serverapparatus 11 is only the planned travel route, the part of the mapinformation that is not stored in the map information storage section25, and the map information having a later creation date-time. Thishelps always use the most recent map information, and also helps reducethe communication time and communication costs.

For example, in a case where at least map information 30 to 38 as shownin FIG. 4 is stored in the map information storage section 25, when acurrent location X and a destination location Y are set and a routesearch is requested, since continuous map information from the currentlocation X to the destination location Y is stored in the mapinformation storage section 25, the navigation apparatus 10 transmits tothe server apparatus 11 information about the creation date-time of themap information 30 to 38. The server apparatus 11 then compares thecreation date-time of the map information 30 to 38 with that of the mapinformation 13 stored in the database 12, and transmits to thenavigation apparatus 10 only those parts of the map information thathave a different creation date-time. Thus, the navigation apparatus 10acquires only updated map information from the server apparatus 11 andstores it in the map information storage section 25. Then, the routesearch is performed within the navigation apparatus 10, and a plannedtravel route 39 as shown in FIG. 4 is calculated.

For example, in a case where map information 30 to 32, 35, and 38 asshown in FIG. 5 is stored in the map information storage section 25,when a current location X and a destination location Y are set and aroute search is requested, since continuous map information from thecurrent location X to the destination location Y is stored in the mapinformation storage section 25, the navigation apparatus 10 transmits tothe server apparatus 11 the creation date-time of the map information 30to 32, 35, and 38, and the operations that are performed thereafter arethe same as those described above. Here, by the use of the mapinformation 30 to 32, 35, and 38, the route search is performed withinthe navigation apparatus 10, and a planned travel route 40 as shown inFIG. 5 is calculated. In this way, although FIG. 5 lacks the mapinformation 34 and 37 shown in FIG. 4, it still has continuous mapinformation from the current location X to the destination location Y,and thus the route search is performed by the use of that mapinformation. This results in a planned travel route 40 different fromthe planned travel route 39 in FIG. 4.

For example, in a case where map information 30 to 32 and 38 as shown inFIG. 6 is stored in the map information storage section 25, when acurrent location X and a destination location Y are set and a routesearch is requested, since continuous map information from the currentlocation X to the destination location Y is not stored in the mapinformation storage section 25, the navigation apparatus 10 transmitsroute search conditions to the server apparatus 11. The server apparatus11 then performs a route search, calculates a planned travel route 39 asshown in FIG. 7, extracts map information 34 and 37 from the database12, and also extracts whatever part of the map information has a latercreation date-time than its counterpart stored in the map informationstorage section 25, and transmits them to the navigation apparatus 10.In this way, the planned travel routes 39 in FIGS. 7 and 4 are the same,but are different from the planned travel route 40 in FIG. 5. Theplanned travel route 39 is shorter than the planned travel route 40, andcan thus be said to be the optimum route.

That is, in a case where, as in FIG. 4, all the neighborhood map up tothe destination location is stored in the map information storagesection 25, the optimum route can be retrieved within the navigationapparatus 10. By contrast, in a case where, as in FIG. 5, onlyparticular parts of the map information up to the destination locationare stored in the map information storage section 25, a route search canbe performed within the navigation apparatus 10, but the retrieved routeis not always the optimum route. Accordingly, to retrieve the optimumroute, it is necessary to perform a route search in the server apparatus11 at extra costs and with longer communication time.

Accordingly, it is preferable that the user be permitted, in step S11,to make the choice of whether to perform a route search on thenavigation apparatus 10 or on the server apparatus 11 even when the mapinformation up to the destination location is stored in the mapinformation storage section 25.

In the embodiment described above, the comparison of the updating dateis performed by the server apparatus. Instead, it is also possible tomake the server apparatus transmit the updating date before transmittingmap information and make the navigation apparatus compare the updatingdate to decide whether or not to receive the map data.

In the present invention, prior to a route search, the type of road tobe searched for may be permitted to be specified. Advisably, this isperformed, for example, after the setting of the destination location.Here, roads can be classified into different types, for example,according to the conditions under which the user desires to use them,such as whether or not to use express ways, whether or not to use tollroads, whether or not to use national roads with priority, etc. Thismakes it possible to search for a planned travel route involving roadsthat meet the conditions under which the user desires to travel, as whenthey do not like to pay any toll, when they want to travel only wideroads, etc.

With this configuration, if continuous map information involving theselected type of road and covering from the start location to thedestination location is not stored in the navigation apparatus, byacquiring from the server apparatus only the planned travel route andthe map information that is not stored in the map information storagesection, it is possible to perform a route search involving the type ofroad desired by the user, and to reduce the communication time andcommunication costs.

In the present invention, when a route search is performed, a plannedtravel route can be calculated based on the degree of traffic congestionand the distance to travel. In this case, traffic information such asthat provided by the VICS (Vehicle Information and Communication System)can be used.

Moreover, in the present invention, when the capacity of the mapinformation storage section 25 becomes scarce, simply unnecessary mapinformation is deleted and new map information is acquired. Here,unnecessary map information includes that having an old acquisition orcreation date-time, or that which is used only infrequently.

Furthermore, in the present invention, when the user drives withoutperforming a route search but with the map information around thecurrent location displayed, if the map information that needs to bedisplayed next as the screen is scrolled is not stored in the mapinformation storage section 25, advisably, the necessary map informationis acquired from the server apparatus 11.

Fourth Embodiment

A fourth embodiment of the invention deals with a navigation apparatusthat reads out map information and neighborhood information from arecording medium having a small capacity. FIG. 10 is a block diagramshowing the configuration of the navigation apparatus 20 of the fourthembodiment. The difference from FIG. 2 is that, in place of the mapinformation storage section 25, there is provided a DVD playback section29. This permits map information to be read out from a DVD having mapinformation on different scales written thereto.

With this configuration, the navigation apparatus 20 acquires items ofguide information, such as service information and advertisements,through the communication controller 21 (receiving means) from theserver apparatus 11, and stores them in the RAM 26 Each item of guideinformation contains guide data, plus search data, of which an exampleis shown in FIG. 11. The guide data consists of the names and locationsof goods and services providers, plus the contents data indicating thegoods and services they provide (for example, for restaurants, the menusthey offer, and, for gas stations, the prices at which they sellgasoline).

Now, the example of the search data shown in FIG. 11 will be described.There are a large number of items of guide information such as serviceinformation and advertisements, and therefore receiving all of themcauses inconveniences in terms of the communication time, communicationcosts, display performance, and searching performance. To avoid theseinconveniences, according to the present invention, prior to downloadingany contents data, only the contents data that fulfils the conditionsset by the user is received. An example of how such conditions are setis the table shown in FIG. 11.

Condition group A includes type conditions A, with number 0 assigned to“no condition”, number 1 to “sports”, number 2 to “leisure”, number 3 to“sales”, number 4 to “pachinko”, and number 5 to “events”. Conditiongroup B includes type conditions B, with number 0 assigned to “nocondition”, number 1 to “markets”, number 2 to “gas stations”, number 3to “sightseeing spots”, and number 4 to “restaurants”. Condition group Cincludes location conditions, with number 0 assigned to “no condition”,number 1 to “within the prefecture”, number 2 to “around the currentlocation”, and number 3 to “around the destination location”. Conditiongroup D includes date-time conditions, with number 0 assigned to “nocondition”, number 1 to “valid time”, number 2 to “valid date”, andnumber 3 to “invalid day of week”.

In each group, the user can select one or more of numbers 1 and greater;if none of these is selected, number 0 assigned to “no condition” isautomatically selected, in which case all the contents data classifiedunder that group is downloaded. The relationship between the conditiongroups A to D is expressed, in logical terms, as follows: (Group A orGroup B) and Group C and Group D.

The search data received before contents data is acquired from theserver apparatus 11 is, for example as shown in FIG. 11, like this:“N-Japanese Restaurant So-and-So/B4/C;13512,03524/D1;1100,2000/D3;3”.This denotes: the name of the target of which the information issearched for is Japanese Restaurant So-and-So; its type condition B isrestaurants; its location is 135 degrees 12 seconds east longitude and35 degrees 24 seconds north latitude; it is open from 11:00 to 20:00;and it is closed on Wednesdays. That is, different conditions areseparated from one another with slashes “/”, and condition item numbersare separated from the data they require with semicolons“;”.

Next, the operation of this embodiment will be described. FIG. 12 is aflow chart showing the operation of the controller 28 (controllingmeans), and FIG. 13 is a flow chart showing the detailed operation ofstep S66 in FIG. 12. When, in step S60, the user sets the conditionsshown in FIG. 11 by operating the operation section (inputting means)24, then, in step S61, the controller 28 stores the set conditions inthe RAM 26.

After step S60, when, in step S62, the controller 28 receives a requestto receive, then, in step S63, the controller 28 receives search datafrom the server apparatus 11. Here, a request to receive is given onvarious occasions; for example, reception may be started when theoperation section 24 is operated (for example, to make preparations fordeparture), every time a predetermined distance has been traveled, everytime a predetermined length of time has elapsed, and when a start signalfrom the server apparatus 11 is received (for example, when a signal fordelivering an advertisement is transmitted from the server apparatus 11as the user approaches a restaurant or convenience store).

Next, in step S64, based on the received search data of one or moreitems of guide information, those items which fulfill type conditions Aor B are selected. This leaves only such items of guide information asfulfill the set types. Next, in step S65, those items which fulfill thelocation conditions are selected. This leaves only such items of guideinformation as fulfill the set locations (areas). Next, in step S66,those items which fulfill the date-time conditions are selected.

Now, the operation performed in step S66 will be described in detailwith reference to FIG. 13. In step S70, if, after the narrowingperformed up to step S65, there still remain items to be processed,then, in step S71, the controller 28 selects the first item of guideinformation as a target of processing. Next, in step S72, the controller28 calculates the predicted date-time at which the location of theselected guide information will be reached. Here, the predicteddate-time is calculated by simulating a drive from the current locationto the location of the selected guide information over the shortestdistance. The simulation here is done with consideration given to thetypes of roads, the number of lanes, the numbers of right and leftturns, the numbers of traffic lights and railroad crossings, the trafficinformation along the route, and the like.

After step S72, if, in step S73, the predicted date-time does notfulfill the set date-time conditions, then, in step S74, this item ofguide information is excluded from those items of which the contentsdata has been selected for downloading. After step S73, in step S75, ifthe location can be reached amply in time (for example, with a 30minutes' margin), the flow proceeds to step S77. If, in step S75, thelocation cannot be reached amply in time, then, in step S76, thecontroller 28 attaches a timer-accompanied flag to that item of guideinformation. A timer-accompanied flag causes the remaining time to bedisplayed when the item of guide information to which it is attached isdisplayed. For example, the time remaining until a bank is closed isdisplayed. In this way, all the items of guide information are subjectedto selection of those which fulfill the date-time conditions (S77, S78,and S72).

Back in FIG. 12, after step S66, in step S67, only the guide data of theitems of guide information that have been narrowed according to theconditions set by the user is acquired, and is stored in the RAM 26. Ofthe guide information stored in the RAM 26, appropriate items aredisplayed as necessary (for example, while the user is driving, whenthey set a route, or when they search for services or advertisements).In addition, for items to which a timer is attached, the remaining timeis displayed.

Incidentally, the operation of the navigation apparatus of the fourthembodiment may be executed before or after the first to thirdembodiments.

As described above, as navigation apparatuses and cellular phones andPDAs incorporating GPS receivers become increasingly widespread, thedemand is increasing for service information distributed throughcommunication, and advertisements are also increasing. With thenavigation apparatus 20 described above, it is possible to easilyselect, from among a large number of items of guide information, onlythose desired by the user. This is effective in terms of thecommunication time, communication costs, display size, and searchingperformance.

INDUSTRIAL APPLICABILITY

Navigation apparatuses according to the present invention not only findapplication in portable and car-mounted use, but can also beincorporated. in cellular phones, PDAs (personal digital assistants),personal computers, and the like.

1. A navigation apparatus comprising a map information storage sectionfor storing map information acquired from a server apparatus, wherein,if continuous map information from a start location to a destinationlocation is not stored in the map information storage section, thenavigation apparatus transmits the start location and the destinationlocation to the server apparatus in order to acquire therefrom mapinformation of unit areas that covers a rectangular area of which twodiagonal vertices coincide with the start and destination locations, thenavigation apparatus then stores the acquired map information in the mapinformation storage section.
 2. The navigation apparatus of claim 1,wherein the acquired map information only contains map information thatis not stored in the map information storage section.
 3. The navigationapparatus of claim 1, wherein the acquired map information contains mapinformation that is not stored in the map information storage sectionand map information of which a version having an earlier creationdate-time is stored in the map information storage section.
 4. Thenavigation apparatus of claim 1, wherein the navigation apparatusreceives search data from the server apparatus and acquires therefromguide data that fulfills a desired search condition.
 5. The navigationapparatus of claim 1, wherein the navigation apparatus receivesdate-time restricting data from the server apparatus and acquirestherefrom guide data that fulfills a desired date-time condition.
 6. Thenavigation apparatus of claim 1, wherein the navigation apparatusreceives time-restricting data and location data from the serverapparatus, then predicts based on the time-restricting data and thelocation data a time at which a target location of route guiding will bereached, and then acquires from the server apparatus guide data thatfulfills the time-restricting data.
 7. The navigation apparatus of claim1, wherein the navigation apparatus acquires a route retrieved by theserver apparatus.
 8. The navigation apparatus of claim 1, wherein aroute is searched for by using the map information stored in the mapinformation storage section, including map information acquired from theserver apparatus.
 9. A navigation apparatus comprising a map informationstorage section for storing map information acquired from a serverapparatus, wherein continuous map information from a start location to adestination location is stored in the map information storage section,and, if there exists any other continuous combination, the navigationapparatus transmits the start location and the destination location tothe server apparatus in order to acquire therefrom map informationconsisting of unit areas that covers a rectangular area of which twodiagonal vertices coincide with the start and destination locations, thenavigation apparatus then storing the acquired map information in themap information storage section.
 10. The navigation apparatus of claim9, wherein the acquired map information only contains map informationthat is not stored in the map information storage section.
 11. Thenavigation apparatus of claim 9, wherein the acquired map informationcontains map information that is not stored in the map informationstorage section and map information of which a version having an earliercreation date-time is stored in the map information storage section. 12.The navigation apparatus of claim 9, wherein the navigation apparatusreceives search data from the server apparatus and acquires therefromguide data that fulfills a desired search condition.
 13. The navigationapparatus of claim 9, wherein the navigation apparatus receivesdate-time restricting data from the server apparatus and acquirestherefrom guide data that fulfills a desired date-time condition. 14.The navigation apparatus of claim 9, wherein the navigation apparatusreceives time-restricting data and location data from the serverapparatus, then predicts based on the time-restricting data and thelocation data a time at which a target location of route guiding will bereached, and then acquires from the server apparatus guide data thatfulfills the time-restricting data.
 15. The navigation apparatus ofclaim 9, wherein the navigation apparatus acquires a route retrieved bythe server apparatus.
 16. The navigation apparatus of claim 9, wherein aroute is searched for by using the map information stored in the mapinformation storage section, including map information acquired from theserver apparatus.
 17. A navigation apparatus comprising a mapinformation storage section for storing map information acquired from aserver apparatus, wherein, if continuous map information from a startlocation to a destination location is stored in the map informationstorage section, a route is searched for, and the navigation apparatusacquires from the server apparatus map information consisting of unitareas that covers an area including and neighboring the retrieved route,the navigation apparatus then storing the acquired map information inthe map information storage section.
 18. The navigation apparatus ofclaim 17, wherein the acquired map information only contains mapinformation that is not stored in the map information storage section.19. The navigation apparatus of claim 17, wherein the acquired mapinformation contains map information that is not stored in the mapinformation storage section and map information of which a versionhaving an earlier creation date-time is stored in the map informationstorage section.
 20. The navigation apparatus of claim 17, wherein thenavigation apparatus receives search data from the server apparatus andacquires therefrom guide data that fulfills a desired search condition.21. The navigation apparatus of claim 17, wherein the navigationapparatus receives date-time restricting data from the server apparatusand acquires therefrom guide data that fulfills a desired date-timecondition.
 22. The navigation apparatus of claim 17, wherein thenavigation apparatus receives date-time restricting data from the serverapparatus and acquires therefrom guide data that fulfills a desireddate-time condition.
 23. The navigation apparatus of claim 17, whereinthe navigation apparatus acquires a route retrieved by the serverapparatus.
 24. The navigation apparatus of claim 17, wherein a route issearched for by using the map information stored in the map informationstorage section, including map information acquired from the serverapparatus.
 25. A server apparatus for transmitting map information to anavigation apparatus, wherein, when the server apparatus receives fromthe navigation apparatus a start location and a destination location,the server apparatus transmits to the navigation apparatus mapinformation consisting of unit areas that covers a rectangular area ofwhich two diagonal vertices coincide with the start and destinationlocations.